MANAMA, Bahrain — The Marine killed in a rocket attack in Iraq Saturday was assigned to the 26th Marine Expeditionary Unit, which has deployed a detachment to Iraq, defense officials said Sunday.

Staff Sgt. Louis F. Cardin, of Temecula, Calif., was assigned to the 2nd Battalion, 6th Marine Regiment, 26th MEU out of Camp Lejeune, N.C., the Pentagon said in a statement.

The U.S.-led coalition fighting the Islamic State announced Sunday that a detachment from the 26th MEU had been deployed to Iraq for "the support of Iraqi security force and coalition ground operations."

The 26th MEU is currently deployed with the Kearsarge Amphibious Ready Group in the 5th Fleet area of operations to maintain regional security, including missions in support of the coalition campaign against the Islamic State group in Iraq and Syria.

Cardin was providing force protection fire support at a recently established coalition fire base near Makhmour, southeast of Iraq’s second largest city, Mosul, when he was killed in a rocket attack, the Pentagon said. The incident is under investigation.

Makhmour, which is controlled by Kurdish forces, is near the frontline with the Islamic State group, which took control of Mosul in 2014. The Washington Post reported the attack was on a small U.S. base on the outskirts of the town within a Kurdish peshmerga facility which is next to an Iraqi army base.

CNN reported the base had only recently become operational and quoted a defense official as saying a "couple hundred" Marines were living in tents there. The official told CNN the Marines had begun moving into the area two weeks ago from the Kearsarge and their movements and firing of practice rounds may have been observed by Islamic State militants.

Iraqi forces have been building up in Makhmour, which is expected to be a staging area for an offensive to retake Mosul.

Several Marines were wounded in Saturday’s attack and being treated. CBS News, citing a military official, reported one of the wounded was in critical condition.

Cardin, 27, joined the Marines in June 2006 and was trained in field artillery, ABC affiliate WWAY in Wilmington, N.C., reported. His awards included the Presidential Unit Citation-Navy, three Afghanistan Campaign medals, an Iraq Campaign Medal and three Sea Service Deployment ribbons, WWAY reported.

Cardin was the second American killed in Iraq in the fight against the Islamic State. Army Master Sgt. Joshua L. Wheeler, a special operations soldier, was killed in a firefight in October during a raid on an Islamic State prison.

"This is the second combat death since the start of Operation Inherent Resolve, and it reminds us of the risks our men and women in uniform face everyday," Pentagon press secretary Peter Cook said in a statement Saturday.